Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Fitzkee, Nicholas C.

Committee Member

Mlsna, Todd E.

Committee Member

Debra, Todd A.

Committee Member

Gordon, Donna M.

Committee Member

Emerson, Joseph

Date of Degree

5-1-2020

Original embargo terms

Complete embargo for 2 years

Document Type

Dissertation - Open Access

Major

Chemistry

Degree Name

Doctor of Philosophy

Degree Name

Doctor of Philosophy (Ph.D)

College

College of Arts and Sciences

College

College of Arts and Sciences

Department

Department of Chemistry

Department

Department of Chemistry

Abstract

Nanoparticles (NPs) have become a key tool in medicine and biotechnology; as drug delivery systems, biosensors, and diagnostic devices. However, the mechanism of biocorona formation on nanoparticle surfaces and their impact on drug delivery remains speculative. Nevertheless, functionalized nanoparticles have demonstrated major success in medical applications; having been shown to effectively treat disease. The mechanistic details of protein behavior on nanoparticle surfaces remain poorly understood to date; due to difficulty in determining the orientation and structure of protein on NPs. Furthermore, surface crowding, orientation, and degree of disorder have been shown to perturb the efficacy of protein on NPs; dramatically reducing their benefits. NMR and other biophysical tools can be used to characterize the nanoparticle-protein surface interactions; leading to a better understanding of the biocorona structure. This dissertation investigates the structure, orientation, and function of proteins adsorbed on gold nanoparticles (P-AuNPs). Using hydrogen-deuterium exchange and methylation studies on P-AuNPs, we have elucidated the structure and orientation of proteins on AuNP surfaces. We have also designed fusion proteins that can effectively mitigate structural-, orientation-, and activity-perturbations of P-AuNPs. The benefits of our fusion protein approach have been verified via enzymatic assay; which monitored the enzymatic activity of these P-AuNPs. Biofilms are defined as surface-anchored, multi-cellular, three-dimensional, bacterial communities. Biofilms have a serious impact on public health; because of their role in infectious diseases and medical device-related infections. S. epidermidis is the most common biofilmorming bacteria. Therefore, understanding the mechanisms of biofilm formation could lead to novel therapeutics which prevent biofilm formation. One of the most recognized proteins in the biofilm formation mechanism is the S. epidermidis autolysin domain. Therefore, we have studied the structure and behavior of S. epidermidis autolysin repeat domain R2 (R2ab) via solution NMR and other biophysical techniques. This study has provided a deeper understanding of how R2ab interacts with foreign surfaces and blood proteins; which could lead to future methods of biofilm prevention. Over the course of this dissertation, the characterization of protein-surface interactions was achieved via solution NMR and other biophysical tools; providing insightful information to the fields of medicine and therapeutics.

URI

https://hdl.handle.net/11668/16698

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